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Abstract:

An endoscopic forceps includes a housing having a shaft attached thereto
that supports a pair of jaws disposed at a distal end thereof. A drive
assembly having a drive shaft with a proximal end is operable to move the
jaws relative to one another from an open to closed positions. A knife
assembly is operable to advance a knife through tissue disposed between
the jaws and includes a flange disposed thereon. A knife lockout is
included that has a flange configured to engage the proximal end of the
drive shaft and a lockout arm configured to engage the flange of the
knife assembly to prevent movement thereof. Movement of the jaws to the
closed position causes the proximal end of the drive shaft to engage the
flange on the lockout which causes the lockout arm to disengage the
flange on the knife assembly to permit advancement of the knife.

Claims:

1. An endoscopic forceps, comprising: a housing having a shaft attached
thereto, the shaft including a pair of jaw members disposed at a distal
end thereof; a drive assembly operable to move the jaw members relative
to one another from an open position wherein the jaw members are disposed
in spaced relation relative to one another to a closed position wherein
the jaw members cooperate to grasp tissue therebetween, the drive
assembly including a drive shaft having a proximal end; a knife assembly
operable to advance a knife through tissue disposed between the jaw
members; and a knife lockout including a first mechanical interface
configured to operably engage the proximal end of the drive shaft and a
second mechanical interface configured to operably engage the knife
assembly and prevent movement thereof, wherein movement of the jaw
members to the closed position causes the second mechanical interface to
disengage the knife assembly.

2. An endoscopic forceps according to claim 1, further comprising a pair
of handles operatively connected to the drive assembly and movable
relative to the housing to actuate the drive assembly to move the jaw
members.

3. An endoscopic forceps according to claim 1, wherein the knife assembly
includes a knife shaft that seats within a cap of an elongated knife
sleeve supported at a proximal end of the housing, the cap including a
flange that extends therefrom that interfaces with the second mechanical
interface of the knife lockout.

4. An endoscopic forceps according to claim 1, wherein engagement of said
first mechanical interface with the proximal end of the drive shaft
causes rotation of the second mechanical interface out of engagement with
the knife assembly.

5. An endoscopic forceps according to claim 1, wherein the knife lockout
includes an adjustment mechanism configured to align the first mechanical
interface of the knife lockout with the disposition of the proximal end
of the drive shaft when the jaw members are in the closed position.

6. An endoscopic forceps according to claim 5, wherein the adjustment
mechanism includes an eccentric nut that aligns the knife lockout.

7. An endoscopic forceps according to claim 1, wherein the knife lockout
includes a spring operable to bias the second mechanical interface of the
knife lockout in an engaged position with the knife assembly.

8. An endoscopic forceps according to claim 1, wherein at least one jaw
member is adapted to connect to an electrosurgical energy source for
providing electrosurgical energy to tissue disposed between the jaw
members.

9. A method of dividing tissue, comprising the steps of: providing a
forceps having: a housing including a shaft attached thereto, the shaft
having a pair of jaw members disposed at a distal end thereof; a drive
assembly operable to move the jaw members relative to one another from an
open position wherein the jaw members are disposed in spaced relation
relative to one another to a closed position wherein the jaw members
cooperate to grasp tissue therebetween, the drive assembly including a
drive shaft having a proximal end; a knife assembly operable to advance a
knife through tissue disposed between the jaw members; and a knife
lockout including a first mechanical interface configured to operably
engage the proximal end of the drive shaft and a second mechanical
interface configured to operably engage the knife assembly and prevent
movement thereof; and actuating the drive assembly to move the jaw
members to the closed position causing the second mechanical interface to
disengage the knife assembly.

10. A method according to claim 9, further comprising the step of biasing
the knife lockout to prevent translation of the knife.

11. A method of separating tissue, comprising the steps of: positioning a
knife lockout to prevent translation of a knife through a knife channel
defined between a pair of jaw members; actuating a drive assembly to
close the pair of jaw members about tissue and position a proximal end of
a drive shaft of the drive assembly to a proximal-most position; and
engaging the knife lockout with the proximal end of the drive shaft to
reposition the knife lockout to allow translation of the knife.

12. A method according to claim 11, further comprising the step of
biasing the knife lockout to prevent translation of the knife.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent application Ser.
No. 12/548,566, filed on Aug. 27, 2009, the entire contents of which are
incorporated herein by reference.

[0003] Electrosurgical forceps utilize both mechanical clamping action and
electrical energy to effect hemostasis by heating tissue and blood
vessels to coagulate, cauterize and/or seal tissue. As an alternative to
open forceps for use with open surgical procedures, many modern surgeons
use endoscopes and endoscopic instruments for remotely accessing organs
through smaller, puncture-like incisions. As a direct result thereof,
patients tend to benefit from less scarring and reduced healing time. As
used herein the term, endoscopic is meant to include laparoscopic.

[0004] Endoscopic instruments are inserted into the patient through a
cannula, or port, which has been made with a trocar. Typical sizes for
cannulas range from three millimeters to twelve millimeters. Smaller
cannulas are usually preferred, which, as can be appreciated, ultimately
presents a design challenge to instrument manufacturers who must find
ways to make endoscopic instruments that fit through the smaller
cannulas.

[0005] Many endoscopic surgical procedures require cutting or ligating
blood vessels or vascular tissue. Due to the inherent spatial
considerations of the surgical cavity, surgeons often have difficulty
suturing vessels or performing other traditional methods of controlling
bleeding, e.g., clamping and/or tying-off transected blood vessels. By
utilizing an endoscopic electrosurgical forceps, a surgeon can either
cauterize, coagulate/desiccate and/or simply reduce or slow bleeding
simply by controlling the intensity, frequency and duration of the
electrosurgical energy applied through the jaw members to the tissue.
Most small blood vessels, e.g., in the range below two millimeters in
diameter, can often be closed using standard electrosurgical instruments
and techniques. However, if a larger vessel is ligated, it may be
necessary for the surgeon to convert the endoscopic procedure into an
open-surgical procedure and thereby abandon the benefits of endoscopic
surgery. Alternatively, the surgeon can seal the larger vessel or tissue.

[0006] It is thought that the process of coagulating vessels is
fundamentally different than electrosurgical vessel sealing. For the
purposes herein, "coagulation" is defined as a process of desiccating
tissue wherein the tissue cells are ruptured and dried. "Vessel sealing"
or "tissue sealing" is defined as the process of liquefying the collagen
in the tissue so that it reforms into a fused mass. Coagulation of small
vessels is sufficient to permanently close them, while larger vessels
need to be sealed to assure permanent closure.

[0007] In order to effectively seal larger vessels (or tissue) two
predominant mechanical parameters should be accurately controlled--the
pressure applied to the vessel (tissue) and the gap distance between the
electrodes or tissue sealing surfaces--both of which are affected by the
thickness of the sealed vessel. More particularly, accurate application
of pressure is important to oppose the walls of the vessel; to reduce the
tissue impedance to a low enough value that allows enough electrosurgical
energy through the tissue; to overcome the forces of expansion during
tissue heating; and to contribute to the end tissue thickness, which is
an indication of a good seal. It has been determined that a typical jaw
gap for fusing vessel walls is optimum between 0.001 and 0.006 inches.
Below this range, the seal may shred or tear and above this range the
lumens may not be properly or effectively sealed.

[0008] With respect to smaller vessels, the pressure applied to the tissue
tends to become less relevant whereas the gap distance between the
electrically conductive surfaces becomes more significant for effective
sealing. In other words, the chances of the two electrically conductive
surfaces touching during activation increases as vessels become smaller.

[0009] It has been found that the pressure range for assuring a consistent
and effective seal is between about 3 kg/cm2 to about 16 kg/cm2 and,
preferably, within a working range of 7 kg/cm2 to 13 kg/cm2.
Manufacturing an instrument that is capable of providing a closure
pressure within this working range has been shown to be effective for
sealing arteries, tissues and other vascular bundles.

[0010] In certain surgical operations, a bipolar forceps is used in
combination with a monopolar forceps or monopolar coagulator to treat
tissue and control bleeding during the surgery. As such and during the
course of a particular operation, a surgeon may be required to substitute
a monopolar instrument for the bipolar instrument, which would typically
involve substitution through the trocar or cannula. As can be appreciated
this may occur on more than one occasion over the course of the
operation, which can be quite time consuming and which may unnecessarily
subject the instruments to possible non-sterile environments.

[0011] Certain surgical instruments have been designed that impede the
advancement of the knife or cutting member when the handles are disposed
in a closed position to avoid unintended actuation or deployment of the
knife through tissue. One such knife lockout design is described in
commonly-owned U.S. patent application Ser. No. 11/540,335 entitled
IN-LINE VESSEL SEALER AND DIVIDER filed by Dumbauld et al., then entire
contents of which is incorporated by reference herein.

SUMMARY

[0012] The present disclosure relates to an endoscopic forceps including a
housing having a shaft attached thereto which supports a pair of jaw
members disposed at a distal end thereof. A drive assembly is included
and is disposed in the housing and is operable to move the jaw members
relative to one another from an open position wherein the jaw members are
disposed in spaced relation relative to one another to a closed position
wherein the jaw members cooperate to grasp tissue therebetween. The drive
assembly includes a drive shaft having a proximal end. A knife assembly
is included and is operable to advance a knife through tissue disposed
between the jaw members. The knife assembly includes at least one
mechanical interface disposed thereon. A knife lockout is also included
having a first mechanical interface configured to operably engage the
proximal end of the drive shaft and a second mechanical interface
configured to operably engage the mechanical interface of the knife
assembly to prevent movement thereof. Movement of the jaw members to the
closed position causes the proximal end of the drive shaft to engage the
first mechanical interface which, in turn, causes the second mechanical
interface to disengage the mechanical interface on the knife assembly to
permit selective advancement of the knife. For example, engagement of the
first mechanical interface with the proximal end of the drive shaft may
cause rotation of the second mechanical interface out of engagement with
the mechanical interface of the knife assembly allowing selective
actuation of the knife.

[0013] In one embodiment, a pair of handles is operatively connected to
the drive assembly; the handles are movable relative to the housing to
actuate the drive assembly to move the jaw members. In another
embodiment, the knife assembly includes a knife shaft that seats within a
cap of an elongated knife sleeve supported at a proximal end of the
housing. The cap may include a flange that extends therefrom that
interfaces with the second mechanical interface of the knife lockout.

[0014] In yet another embodiment, the knife lockout may include an
adjustment mechanism that precisely aligns the first mechanical interface
of the knife lockout with the disposition of proximal end of the drive
shaft when the jaw members are in the closed position. The adjustment
mechanism may include an eccentric nut that is manually adjustable to
align the knife lockout after assembly.

[0015] The knife lockout may also include a spring to bias the second
mechanical interface of the knife lockout in an engaged position with the
mechanical interface of the knife assembly.

[0016] The present disclosure also relates to a method of manufacturing a
device for dividing vessels or tissue and includes the initial step of:
providing a forceps having a housing including a shaft attached thereto
that supports a pair of jaw members and at a distal end thereof. A drive
assembly is disposed in the housing and is operable to move the jaw
members relative to one another from an open position wherein the jaw
members and are disposed in spaced relation relative to one another to a
closed position wherein the jaw members and cooperate to grasp tissue
therebetween. The drive assembly includes a drive shaft having a proximal
end. A knife assembly is included and is operable to advance a knife
through tissue disposed between the jaw members and. The knife assembly
includes a mechanical interface disposed thereon. A knife lockout is
included that has a first mechanical interface configured to operably
engage the proximal end of the drive shaft and a second mechanical
interface configured to operably engage the mechanical interface of the
knife assembly and prevent movement thereof.

[0017] The method also includes the step of actuating the drive assembly
to move the jaw members to the closed position causing the proximal end
of the drive shaft to engage the first mechanical interface which, in
turn, causes the second mechanical interface to disengage the mechanical
interface on the knife assembly and permit selective advancement of the
knife.

[0018] Another method according to the present disclosure includes a
method for separating tissue which includes the steps of: positioning a
knife lockout to prevent translation of a knife blade through a knife
channel defined between a pair of jaw members; actuating a drive assembly
to close the pair of jaw members about tissue and position a proximal end
of a drive shaft of the drive assembly to a proximal-most position; and
engaging a first mechanical interface extending from the knife lockout
with the proximal end of the drive shaft to reposition a second
mechanical interface of the knife lockout to allow translation of the
knife blade.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Various embodiments of the subject instrument are described herein
with reference to the drawings wherein:

[0020]FIG. 1A is a top, perspective view of an endoscopic forceps shown
in an open configuration and including a housing, a handle assembly, a
shaft and an end effector assembly according to an embodiment of the
present disclosure;

[0021]FIG. 1B is a top, perspective view of the endoscopic forceps of
FIG. 1A showing the end effector assembly in a closed configuration an
embodiment of the present disclosure;

[0022] FIG. 2A is an enlarged, top view of the forceps of FIG. 1A showing
the disposition of the internal components when the forceps is in an open
configuration;

[0023] FIG. 2B is an enlarged, top view of the forceps of FIG. 1B showing
the disposition of the internal components when the forceps is in a
closed configuration;

[0024]FIG. 3A is an enlarged, top view showing the knife actuator after
actuation;

[0025]FIG. 3B is a greatly-enlarged, side cross sectional view of the end
effector assembly showing the position of the knife after actuation;

[0026]FIG. 4A is a greatly-enlarged, perspective view of the bottom jaw
of the end effector assembly with parts separated;

[0027] FIG. 4B is a greatly-enlarged, perspective view of the top jaw of
the end effector assembly with parts separated;

[0028]FIG. 5 is a greatly-enlarged, perspective view of the elongated
shaft for housing various moving parts of the drive assembly and knife
assembly;

[0029]FIG. 6 is an internal view of an alternate embodiment of a forceps
according to the present disclosure showing a knife lockout disposed in
an engaged position;

[0030] FIG. 7 is an internal view of the embodiment of FIG. 6 showing the
knife lockout disposed in a disengaged position by virtue of the movement
of the drive shaft; and

[0031] FIG. 8 is an enlarged, exploded view of the knife lockout of FIG.
6.

DETAILED DESCRIPTION

[0032] During certain tissue treatment procedures that require transaction
of tissue, it may prove useful to employ a knife lockout to prevent
unintended advancement of the knife or cutting mechanism through the
tissue before the tissue is treated. Moreover, in some instances it may
prove useful to prevent translation of the knife when the jaw members are
not fully clamped about tissue or are incorrectly clamped about tissue
(e.g., too much tissue between jaw members). In this instance, preventing
translation of the knife or cutting mechanism will prevent the knife from
jamming, miscuing, buckling, pinching or de-railing upon translation or
retraction of the knife blade. In some instances, improper deployment or
retraction of the knife may render the forceps unusable.

[0033] Turning now to FIGS. 1A and 1B, one embodiment of an endoscopic
electrosurgical forceps 10 is shown for use with various surgical
procedures and generally includes a housing 20, a handle assembly 30, a
rotating assembly 80, a knife assembly 70 and an end effector assembly
100 which mutually cooperate to grasp, seal and divide tubular vessels
and vascular tissue. Although the majority of the figure drawings depict
a forceps 10 for use in connection with endoscopic surgical procedures,
the present disclosure may be used for more traditional open surgical
procedures.

[0034] Forceps 10 includes a shaft 12 which has a distal end 16
dimensioned to mechanically engage the end effector assembly 100 and a
proximal end 14 which mechanically engages the housing 20. Details of how
the shaft 12 connects to the end effector assembly 100 are described in
more detail below. The proximal end 14 of shaft 12 is received within the
housing 20 and the connections relating thereto are also described in
detail below. In the drawings and in the descriptions which follow, the
term "proximal", as is traditional, will refer to the end of the forceps
10 which is closer to the user, while the term "distal" will refer to the
end which is further from the user.

[0035] Forceps 10 also includes an electrosurgical cable 310 that connects
the forceps 10 to a source of electrosurgical energy, e.g., a generator
(not shown). Generators such as those sold by Covidien, located in
Boulder Colorado may be used as a source of both bipolar electrosurgical
energy for sealing vessel and vascular tissues as well as monopolar
electrosurgical energy which is typically employed to coagulate or
cauterize tissue. It is envisioned that the generator may include various
safety and performance features including isolated output, impedance
control and/or independent activation of accessories.

[0036] Handle assembly 30 includes two movable handles 30a and 30b
disposed on opposite sides of housing 20. Handles 30a and 30b are movable
relative to one another to actuate the end effector assembly 100 as
explained in more detail below with respect to the operation of the
forceps 10.

[0037] Rotating assembly 80 is mechanically coupled to housing 20 and is
rotatable approximately 90 degrees in either direction about a
longitudinal axis "A." Rotating assembly 80, when rotated, rotates shaft
12, which, in turn, rotates end effector assembly 100. Such a
configuration allows end effector assembly 100 to be rotated
approximately 90 degrees in either direction with respect to housing 20.

[0038] As mentioned above, end effector assembly 100 is attached at the
distal end 16 of shaft 12 and includes a pair of opposing jaw members 110
and 120 (see FIGS. 4A and 4B). Handles 30a and 30b of handle assembly 30
ultimately connect to drive assembly 60 (see FIG. 2A) which, together,
mechanically cooperate to impart movement of the jaw members 110 and 120
from a first, open position wherein the jaw members 110 and 120 are
disposed in spaced relation relative to one another, to a second,
clamping or closed position wherein the jaw members 110 and 120 cooperate
to grasp tissue therebetween.

[0039] Turning now to the more detailed features of the present disclosure
as described with respect to FIGS. 1A-5, handles 30a and 30b each include
an aperture 33a and 33b, respectively, defined therein which enables a
user to grasp and move each respective handle 30a and 30b relative to one
another. Handles 30a and 30b also include ergonomically-enhanced gripping
elements 39a and 39b, respectively, disposed along an outer edge thereof
which are designed to facilitate gripping of the handles 30a and 30b
during activation. It is envisioned that gripping elements 39a and 39b
may include one or more protuberances, scallops and/or ribs to enhance
gripping.

[0040] As best illustrated in FIG. 1A, handles 30a and 30b are configured
to extend outwardly on opposite sides from a transverse axis "B" defined
through housing 20 which is perpendicular to longitudinal axis "A".
Handles 30a and 30b are movable relative to one another in a direction
parallel to axis "B" to open and close the jaw members 110 and 120 as
needed during surgery. Details relating to the inner-working components
of forces 10 are disclosed in commonly-owned U.S. patent application Ser.
No. 11/540,335, the entire contents of which being incorporated by
reference herein. This forceps style is commonly referred to as an
"in-line" or hemostat style forceps. In-line hemostats or forceps are
more commonly manufactured for open surgical procedures and typically
include a pair of shafts having integrally coupled handles which are
movable relative to one another to open and close the jaw members
disposed at the distal end thereof.

[0041] As best seen in FIGS. 2A and 2B, the distal end of each handle 30a
and 30b is selectively moveable about pivot pins 34a and 34b attached to
a distal end 21 of the housing 20 to actuate the jaw members 110 and 120.
Movement of the handles 30a and 30b away from one another (and the
housing 20) unlocks and opens the handles 30a and 30b and, in turn, the
jaw members 110 and 120 for subsequent grasping or re-grasping of tissue.
In one embodiment, the handles 30a and 30b may be biased in an open
configuration to facilitate handling and manipulation of the jaw members
110 and 120 within an operative field. Various spring-like mechanisms are
contemplated which may be utilized to accomplish this purpose.

[0042] Movable handles 30a and 30b are designed to provide a distinct
lever-like mechanical advantage over conventional handle assemblies. The
enhanced mechanical advantage for actuating the jaw members 110 and 120
is gained by virtue of the unique position and combination of several
inter-cooperating elements which reduce the overall user forces necessary
to obtain and maintain the jaw members 110 and 120 under ideal operating
pressures of about 3 kg/cm2 to about 16 kg/cm2. Details relating to the
working components the handle assembly and drive assembly are disclosed
in above-mentioned U.S. patent application Ser. No. 11/540,335. In other
words, it is envisioned that the combination of these elements and their
positions relative to one another enables the user to gain lever-like
mechanical advantage to actuate the jaw members 110 and 120 enabling the
user to close the jaw members 110 and 120 with lesser force while still
generating the required forces necessary to effect a proper and effective
tissue seal.

[0043] As shown in FIGS. 4A, 4B, and 5, the end effector assembly 100 is
designed as a bilateral assembly, i.e., both jaw members 110 and 120
pivot relative to one another about a pivot pin 185 disposed
therethrough. Each jaw member 110 and 120 includes a corresponding flange
113 and 123 that pivots about a pivot pin 185 disposed between the jaw
members 110 and 120 upon translation of a drive rod 180 as explained in
more detail below.

[0044] More particularly, jaw members 110 and 120 include proximal flanges
113 and 123, respectively, which each include an elongated angled slot
181a and 181b, respectively, defined therethrough. Drive pin 180 mounts
jaw members 110 and 120 to the end of a rotating shaft 18 and within a
cavity 17' defined at the distal ends 17a and 17b of drive actuator or
sleeve 17 (See FIG. 5).

[0045] More particularly, upon actuation of the drive assembly 60, the
drive sleeve 17 reciprocates which, in turn, causes the drive pin 180 to
ride within slots 181a and 181b to open and close the jaw members 110 and
120 as desired. The jaw members 110 and 120, in turn, pivot about pivot
pin 185 disposed through respective pivot holes 186a and 186b defined
within flanges 113 and 123 of the jaw members 110 and 120. As can be
appreciated, squeezing handles 30a and 30b toward the housing 20 pulls
drive sleeve 17 and drive pin 180 proximally to close the jaw members 110
and 120 about tissue grasped therebetween and pushing the sleeve 17
distally opens the jaw members 110 and 120 for grasping purposes.

[0046] Flanges 113 and 123 of jaw members 110 and 120, respectively, are
positioned in an abutting relationship with one another. Flanges 113, 123
are assembled and engaged via pivot pin 185 disposed through apertures
186a, and 186b, respectively. Further, flanges 113 and 123 are pivotable
about one another via drive pin 180 disposed through slots 181a and 181b
and of flanges 113 and 123, respectively. A knife path may be defined
between flanges 113 and 123 that longitudinally aligns with knife
channels 115a and 115b defined within jaw members 110 and 120, such that
knife blade 190 travels in a substantially straight path through knife
channels 115a and 115b defined in jaw members 110 and 120, respectively.

[0047] As shown in FIG. 4B, jaw member 110 also includes a support base
119 which extends distally from flange 113 and which is configured to
support an insulative plate 119' thereon. Insulative plate 119', in turn,
is configured to support an electrically conductive tissue engaging
surface or sealing plate 112 thereon. Sealing plate 112 may be affixed
atop the insulative plate 119' and support base 119 in any known manner
in the art, snap-fit, over-molding, stamping, ultrasonically welded, etc.
Support base 119 together with the insulative plate 119' and electrically
conductive tissue engaging surface 112 are encapsulated by an outer
insulative housing 114. Outer housing 114 includes a cavity 114a that is
dimensioned to securely engage the electrically conductive sealing
surface 112 as well as the support base 119 and insulative plate 119'.
This may be accomplished by stamping, by overmolding, by overmolding a
stamped electrically conductive sealing plate and/or by overmolding a
metal injection molded seal plate. All of these manufacturing techniques
produce jaw member 110 having an electrically conductive surface 112
which is substantially surrounded by an insulating substrate 114.

[0048] The electrically conductive surface or sealing plate 112 and the
outer housing 114, when assembled, form longitudinally-oriented knife
channel 115a defined therethrough for reciprocation of the knife blade
190. It is envisioned that the knife channel 115a cooperates with
corresponding knife channel 115b defined in jaw member 120 to facilitate
longitudinal extension of the knife blade 190 along a preferred cutting
plane to effectively and accurately separate the tissue along the formed
tissue seal. As discussed above, when knife blade 190 is deployed, at
least a portion of knife blade 190 advances into knife channels 115a and
115b. Handle 30a may include a lockout flange (not shown) which prevents
actuation of the knife assembly 70 when the handle 30a is open thus
preventing accidental or premature activation of the knife blade 190
through the tissue. A more detailed discussion of the lockout flange is
discussed in above-mentioned U.S. patent application Ser. No. 11/540,335.

[0049] As explained above and as illustrated in FIGS. 4A and 4B, the knife
channel 115 is formed when the jaw members 110 and 120 are closed. In
other words, the knife channel 115 includes two knife channel
halves--knife channel half 115a disposed in sealing plate 112 of jaw
member 110 and knife channel half 115b disposed sealing plate 122 of jaw
member 120. Knife channel 115 may be configured as a straight slot with
no degree of curvature which, in turn, causes the blade 190 to move
through the tissue in a substantially straight fashion. Alternatively and
as shown, the knife channel 115 may be curved which has certain surgical
advantages.

[0050] As mentioned above, when the jaw members 110 and 120 are closed
about tissue, knife channels 115a and 115b form a complete knife channel
115 to allow longitudinal extension of the knife blade 190, from the
knife path, in a distal fashion to sever tissue along a tissue seal.
Knife channel 115 may be completely disposed in one of the two jaw
members, e.g., jaw member 120, depending upon a particular purpose. It is
also envisioned that jaw member 120 may be assembled in a similar manner
as described above with respect to jaw member 110.

[0051] FIGS. 6-8 show another embodiment of a knife lockout 1200 for use
with forceps 10. Unlike the described knife lockout element of
commonly-owned U.S. patent application Ser. No. 11/540,335 that prevents
advancement of the knife blade 190 when the handles 30a and 30b of
forceps 10 are disposed in an open position, lockout 1200 prevents
advancement of the knife blade 190 when the jaw members 110 and 120 are
disposed in an open position. More particularly, the knife lockout 1200
operably communicates with the drive shaft 1017 such that the position of
the drive shaft 1017 (which regulates the opening and closing of the jaw
members 110 and 120) dictates a user option for selective advancement of
the knife assembly 70. In other words, the disposition of knife lockout
1200 (e.g., "engaged" or "disengaged") is dependent on the position of
the drive shaft 1017 and not necessarily the position of the handles
1030a and 1030b. As explained below, the manufacturer can precisely
orient an eccentric nut 1225 of the lockout 1200 such that the knife
shaft 1071 (and therefore knife blade 190) can only be advanced when the
proximal end 1017' of the drive shaft 1017 is fully retracted and the jaw
members 110 and 120 are fully closed about tissue.

[0052] More particularly, and with respect to FIG. 6, forceps 1000 is
similar to the above described forceps 10 with only those exceptions
being discussed hereinbelow. Forceps 1000 includes movable handles 1030a
and 1030b which together cooperate to actuate the drive assembly (not
shown in this embodiment) as discussed above with respect to FIGS. 2A and
2B. In this envisioned embodiment, a proximal end 1017' of the drive
shaft 1017 is configured to extend proximally relative to the drive
assembly to permit engagement with the knife lockout 1200 (as explained
in detail below) when the jaw members 110 and 120 are fully closed about
tissue.

[0053] As shown in FIGS. 6 and 8, the knife assembly 70 is configured to
extend proximally and settle within a proximal end of the housing 1020.
The knife shaft 1071 includes a T-shaped proximal end 1075 that seats
within a cap 1110 of an elongated knife support sleeve 1115 having a
flange 1110 that extends therefrom. Details relating to the interaction
of the cap 1100 and the knife lockout 1200 are explained below.

[0054] As shown in FIG. 8, knife lockout 1200 includes a lever 1210 that
is configured to be supported within the housing 1020 and includes a
lockout base 1213 having a lockout arm 1214, a spring arm 1216 and a
flange 1212 that extend outwardly therefrom. Flange 1212 is configured to
operably engage the proximal end 1017' of drive shaft 1017 when the jaw
members 110 and 120 are moved to a fully closed position (See FIG. 7).
Upon contact, the flange 1212 is rotated proximally which, in turn,
rotates the lockout base 1210 and lockout arm 1214 clockwise such that
the proximal end 1214' of the lockout arm 1214 disengages from the flange
1110 of the knife assembly cap 1100. When disengaged, the knife assembly
70 is selectively actuatable by the user to sever tissue disposed between
the jaw members 110 and 120. The knife assembly 70 may be spring-biased
to return to a fully retracted position upon release thereof.

[0055] It is important to note that the knife lockout 1200 is also spring
biased such that when the jaw members 110 and 120 are moved from their
fully closed position and the proximal end 1017' of the drive shaft 1017
no longer engages the flange 1212, the spring arm 1216 forces the lockout
arm 1214 counter-clockwise to reengage the flange 1110 of the knife
assembly 70 thereby preventing movement thereof. The spring arm 1216 is
biased against the inner periphery of the housing 1020. As can be
appreciated, this feature insures that the disposition of the jaw members
110 and 120 and not the disposition of the handles 1030a and 1030b
dictates whether the knife assembly 70 may be actuated to separate
tissue. In other words, the jaw members must be fully closed in order for
the knife 190 to become available for tissue separation.

[0056] An adjustment mechanism, e.g., an eccentric adjustment nut 1225, is
configured to allow precise alignment of the knife lockout 1200 with the
fully retracted position of the proximal end 1017' of the drive shaft
1017. This allows a manufacturer to precisely adjust the relative
position of the flange 1212 of the knife lockout 1200 with respect to the
position of the proximal end 1017' of the drive shaft 1017 after assembly
of the internal components of the forceps 1000 to assure proper
disengagement of the knife lockout 1200 when the jaw members 110 and 120
are fully closed. The eccentric adjustment nut 1225 includes a pair of
opposing slits 1227 that are configured to facilitate rotation of the nut
1225 which, in turn, precisely aligns the lockout 1200. The eccentric nut
1225 is configured to seat within an aperture defined with the lockout
base 1213. A locking bolt 1220 is utilized to lock the nut 1225 in place
after alignment of the lockout 1200. Once the housing 1020 is fully
assembled, the eccentric adjustment nut 1225 and locking bolt 1220 are
secured into place. The locking bolt 1220 may be integrally associated
with the housing 20 or may be eliminated and replaced with an alternative
boss (not shown).

[0057] Other types of alignment mechanisms are also contemplated and
include: a living hinge and set screw combination that may be configured
to vary the angle of pivot of the lockout 1200; a diagonal slot
arrangement that allows precise alignment of the lockout 1200 which is
then locked by a set screw; a gear and ratchet alignment device which can
be precisely aligned and then locked; a crush feature that locks the
lockout device 1200 in an aligned configuration; one or more shims that
lock the lockout in precise configuration after alignment; and/or a
flexible post and set screw arrangement that aligns and locks the lockout
device 1200.

[0058] It is contemplated that the above described forceps 100 may be
configured in combination with any of the aforementioned features of the
forceps 10 described with respect to FIG. 1A-5 or with respect to any of
the features described in above-mentioned and commonly-owned U.S. patent
application Ser. No. 11/540,335. For example, the forceps 1000 may
include a safety lockout, e.g., lockout that prevents activation of one
or both switches depending upon the disposition of the jaw members 110
and 120.

[0059] A monopolar lockout may also be included that prevents activation
of the monopolar switch when the jaw members 110 and 120 are disposed in
the open position. The monopolar lockout may include a mechanical
interface disposed on one or both of the handles 1030a, 1030b that
prevents activation of the monopolar switch when the handles 1030a, 1030b
are disposed in an open or first position relative to the housing 1020
and permits activation of the monopolar switch when the handles 1030a,
1030b are disposed in a closed or second position relative to the housing
1020. For example, a pressure activated safety switch (not shown) may be
disposed in the housing 1020 and movement of the handles 1030a, 1030b
from the open position to the closed position and/or movement of the jaw
members from the open to closed position relative to the housing 1020
closes the pressure activated safety switch to allow activation of the
monopolar switch.

[0060] In another example, the monopolar lockout may include a mechanical
interface disposed on one (or both) of the handles 1030a and 1030b that
prevents activation of the monopolar switch (or bipolar switch or both
switches) when the handles 1030a and 1030b are disposed in a first
position relative to the housing 1020 and permits activation of one or
both switch when the handles 1030a and 1030b are disposed in a second
position relative to the housing.

[0061] The present disclosure also relates to a method of manufacturing a
device for dividing tissue including the initial step of providing a
forceps 1000 having a housing 1020 including a shaft 12 attached thereto
that supports a pair of jaw members 110 and 120 at a distal end thereof.
A drive assembly 60 is disposed in the housing 1020 and is operable to
move the jaw members 110 and 120 relative to one another from an open
position wherein the jaw members 110 and 120 are disposed in spaced
relation relative to one another to a closed position wherein the jaw
members 110 and 120 cooperate to grasp tissue therebetween. The drive
assembly 60 includes a drive shaft 1017 having a proximal end 1017'. A
knife assembly 70 is included and is operable to advance a knife 190
through tissue disposed between the jaw members 110 and 120. The knife
assembly 70 includes a mechanical interface, e.g., flange 1110, disposed
thereon. A knife lockout 1200 is included that has a first mechanical
interface, e.g., flange 1212, configured to operably engage the proximal
end 1017' of the drive shaft 1017 and a second mechanical interface,
e.g., lockout arm 1214, configured to operably engage the mechanical
interface 1110 of the knife assembly 70 and prevent movement thereof.

[0062] The method also includes the step of actuating the drive assembly
60 to move the jaw members 110 and 120 to the closed position causing the
proximal end 1017' of the drive shaft 1017 to engage the first mechanical
interface 1212 which, in turn, causes the second mechanical interface
1214 to disengage the mechanical interface 1110 on the knife assembly 70
and permit selective advancement of the knife 190.

[0063] Another method according to the present disclosure includes a
method for separating tissue which includes the steps of: positioning a
knife lockout 1200 to prevent translation of a knife blade 190 through a
knife channel 115 defined between a pair of jaw members 110 and 120;
actuating a drive assembly 60 to close the pair of jaw members 110 and
120 about tissue and position a proximal end 1017' of a drive shaft 1017
of the drive assembly 60 to a proximal-most position; and engaging a
first mechanical interface 1212 extending from the knife lockout 1200
with the proximal end 1017' of the drive shaft 1017 to reposition a
second mechanical interface 1214 of the knife lockout 1200 to allow
translation of the knife blade 190.

[0064] From the foregoing and with reference to the various figure
drawings, those skilled in the art will appreciate that certain
modifications can also be made to the present disclosure without
departing from the scope of the same. For example, it may be preferable
to add other features to the forceps 10, 1000, e.g., an articulating
assembly to axially displace the end effector assembly 100 relative to
the elongated shaft 12. While several embodiments of the disclosure have
been shown in the drawings, it is not intended that the disclosure be
limited thereto, as it is intended that the disclosure be as broad in
scope as the art will allow and that the specification be read likewise.
Therefore, the above description should not be construed as limiting, but
merely as exemplifications of particular embodiments. Those skilled in
the art will envision other modifications within the scope and spirit of
the claims appended hereto.